The present invention relates to a new and distinct hybrid cultivar of mandarin tree (Citrus reticulata) designated ‘Marathon’. ‘Marathon’ can be distinguished at least by its seedless, easy-to-peel, and well-colored fruit, the early maturation of its fruit, and the above average length that its fruit can be held on the tree without deterioration.
‘Marathon’ was derived from a seedling tree that was itself selected from a family of hybrids that was produced by a cross performed at Lake Alfred, Fla. in the spring of 2005. The seed parent was the mandarin variety ‘Daisy’ (unpatented), which was produced by crossing the mandarin varieties ‘Fortune’ (unpatented) and ‘Fremont’ (unpatented). The pollen parent was the small-fruited mandarin cultivar ‘Seedless Kishu’ (unpatented), which is also known as ‘Mukakukishu’ in Japan. The original seedling tree was planted in the field at Lake Alfred, Fla. in the spring of 2007 and was first selected during the autumn of 2013. ‘Marathon’ was first asexually propagated in October, 2014 at Vero Beach, Fla. by top working it onto existing red grapefruit trees growing on ‘Swingle’ citrumelo (unpatented) rootstock. ‘Marathon’ was also grafted onto sour orange seedling rootstocks that were planted in both Vero Beach, Fla. and Lake Alfred, Fla.